Beyond Thirty (also known as The Lost Continent) is a science fiction novella by Edgar Rice Burroughs, first published in 1916. The story is set in a future where the Western Hemisphere has cut off all contact with the rest of the world after a devastating war. The protagonist, Lieutenant Jefferson Turck of the Pan-American Navy, accidentally crosses the forbidden 30th meridian and discovers the ruins of what was once Europe.

He finds that Europe has regressed into barbarism and tribal warfare, with civilization having collapsed long ago. Turck's journey takes him through dangerous territories and strange encounters, including a romance with a British woman named Victory. The story explores themes of isolationism, the decline of civilization, and the clash between progress and decay.

It's a classic example of early 20th-century speculative fiction, with Burroughs imagining the long-term consequences of global war and technological collapse.